1. _That thou shouldst not here looke to find any exact, accurate Treatise, since this discourse was but the fruit of some lighter studies, and those too hudled up in a short time, being first thought of and finished in the space of some few weekes, and therefore you cannot in reason expect, that it should be so polished, as perhaps, the subject would require, or the leisure of the Author might have done it._ 2. _To remember that I promise onely probable arguments for the proofe of this opinion, and therefore you must not looke that every consequence should be of an undeniable dependance, or that the truth of each argument should be measured by its necessity. I grant that some Astronomicall appearances may possibly be solved otherwise then here they are. But the thing I aime at is this, that probably they may so be solved, as I have here set them downe: Which, if it be granted (as I thinke it must) then I doubt not, but the indifferent reader will find some satisfaction in the maine thing that is to be proved._ _Many ancient Philosophers of the better note, have formerly defended this assertion, which I have here laid downe, and it were to be wished, that some of us would more apply our endeavours unto the examination of these old opinions, which though they have for a long time lien neglected by others, yet in them may you finde many truths well worthy your paines and observation. Tis a false conceit, for us to thinke, that amongst the ancient variety and search of opinions, the best hath still prevailed. Time (saith the learned _Verulam_) seemes to be of the nature of a river or streame, which carrieth downe to us that which is light, or blowne up, but sinketh that which is weighty and solid._ _It is my desire that by the occasion of this discourse, I may raise up some more active spirit to a search after other hidden and unknowne truthes. Since it must needes be a great impediment unto the growth of sciences, for men still so to plod on upon beaten principles, as to be afraid of entertaining any thing that may seeme to contradict them. An unwillingnesse to take such things into examination, is one of those errours of learning in these times observed by the judicious _Verulam_. Questionlesse there are many secret truths, which the ancients have passed over, that are yet left to make some of our age famous for their discovery._ _If by this occasion I may provoke any reader to an attempt of this nature, I shall then thinke my selfe happy, and this work successefull._ Farewell. [Decoration] The First Proposition, by way of Preface. _That the strangenesse of this opinion is no sufficient reason why it should be rejected, because other certaine truths have beene formerly esteemed ridiculous, and great absurdities entertayned by common consent._